Electronic products, such as televisions, telephones, radios, computers and the like, use semiconductor devices including transistors, capacitors, diodes and resistors. These semiconductor devices such as, for example, resistors may play an important role in the operations of an electronic circuit in the electronic product.
Some electronic devices use resistors having large resistances, thus, using metallic materials as an interconnection material may be inappropriate. In other words, a conductive material having a small resistivity may be used and a length of the resistor may be increased to provide the desired resistance. Increasing the length of the resistor may cause the size of the semiconductor chip to increase (i.e. an increase in chip area), which may increase production costs of the semiconductor device. Accordingly, many semiconductor products use polysilicon, a material used for a gate electrode or a contact plug, as a material for the resistor. Since polysilicon is one of materials that may be used in the semiconductor products and has proper resistivity, using polysilicon as a resistor material may allow the chip area of the device to be maintained and may reduce the amount of new materials introduced into the device.
Semiconductor devices having resistors including polysilicon and related methods are discussed in U.S. patent application Publication No. 2004/0175924 entitled Semiconductor Device Having Resistor and Method of Fabricating the Same. A method of fabricating resistors and floating gates of a FLASH memory using the same material is discussed therein. In particular, the floating gate is fabricated using a photolithographic/etching process. However, as semiconductor devices become more highly integrated, methods of forming floating gate electrodes without using a photolithographic/etching process may be desirable, for example, as discussed in A novel self-aligned shallow trench isolation cell for 90 nm 4 Gbit NAND FLASH EEPROMs (2003 symposium on VLSI technology digest of technical papers, pp. 89–90). As discussed therein, a polysilicon layer used as the floating gate electrode is completely removed from a surface of a device isolation layer in the peripheral circuit region where the resistor is formed. Thus, by definition, the resistor and the floating gate electrode cannot be fabricated using the same process.
Furthermore, uniformity of resistance is another important characteristic associated with a resistor of an electronic device. The uniformity of resistance can be affected by, for example, structural uniformity, such as a thickness of the resistor, resistivity uniformity of the resistor material, contact resistance between the resistor and the interconnection, and the like.